text: /*
   * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1.  Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   * 2.  Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
   *     its contributors may be used to endorse or promote products derived
   *     from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
   * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "config.h"
  #include "platform/fonts/FontFallbackList.h"
  
  #include "platform/FontFamilyNames.h"
  #include "platform/fonts/FontCache.h"
  #include "platform/fonts/FontDescription.h"
  #include "platform/fonts/FontFamily.h"
  #include "platform/fonts/SegmentedFontData.h"
  #include "wtf/unicode/CharacterNames.h"
  
  namespace blink {
  
  FontFallbackList::FontFallbackList()
      : m_pageZero(0)
      , m_cachedPrimarySimpleFontData(0)
      , m_fontSelector(nullptr)
      , m_fontSelectorVersion(0)
      , m_familyIndex(0)
      , m_generation(FontCache::fontCache()->generation())
      , m_pitch(UnknownPitch)
      , m_hasLoadingFallback(false)
  {
  }
  
  void FontFallbackList::invalidate(PassRefPtrWillBeRawPtr<FontSelector> fontSelector)
  {
      releaseFontData();
      m_fontList.clear();
      m_pageZero = 0;
      m_pages.clear();
      m_cachedPrimarySimpleFontData = 0;
      m_familyIndex = 0;
      m_pitch = UnknownPitch;
      m_hasLoadingFallback = false;
      m_fontSelector = fontSelector;
      m_fontSelectorVersion = m_fontSelector ? m_fontSelector->version() : 0;
      m_generation = FontCache::fontCache()->generation();
      m_widthCache.clear();
  }
  
  void FontFallbackList::releaseFontData()
  {
      unsigned numFonts = m_fontList.size();
      for (unsigned i = 0; i < numFonts; ++i) {
          if (!m_fontList[i]->isCustomFont()) {
              ASSERT(!m_fontList[i]->isSegmented());
              FontCache::fontCache()->releaseFontData(toSimpleFontData(m_fontList[i]));
          }
      }
  }
  
  void FontFallbackList::determinePitch(const FontDescription& fontDescription) const
  {
      for (unsigned fontIndex = 0; ; ++fontIndex) {
          const FontData* fontData = fontDataAt(fontDescription, fontIndex);
          if (!fontData) {
              // All fonts are custom fonts and are loading. Fallback should be variable pitch.
              m_pitch = VariablePitch;
              break;
          }
  
          const SimpleFontData* simpleFontData;
          if (fontData->isSegmented()) {
              const SegmentedFontData* segmentedFontData = toSegmentedFontData(fontData);
              if (segmentedFontData->numRanges() != 1 || !segmentedFontData->rangeAt(0).isEntireRange()) {
                  m_pitch = VariablePitch;
                  break;
              }
              simpleFontData = segmentedFontData->rangeAt(0).fontData().get();
          } else {
              simpleFontData = toSimpleFontData(fontData);
          }
          if (!fontData->isLoadingFallback()) {
              m_pitch = simpleFontData->pitch();
              break;
          }
      }
  }
  
  bool FontFallbackList::loadingCustomFonts() const
  {
      if (!m_hasLoadingFallback)
          return false;
  
      unsigned numFonts = m_fontList.size();
      for (unsigned i = 0; i < numFonts; ++i) {
          if (m_fontList[i]->isLoading())
              return true;
      }
      return false;
  }
  
  bool FontFallbackList::shouldSkipDrawing() const
  {
      if (!m_hasLoadingFallback)
          return false;
  
      unsigned numFonts = m_fontList.size();
      for (unsigned i = 0; i < numFonts; ++i) {
          if (m_fontList[i]->shouldSkipDrawing())
              return true;
      }
      return false;
  }
  
  const SimpleFontData* FontFallbackList::determinePrimarySimpleFontData(const FontDescription& fontDescription) const
  {
      bool shouldLoadCustomFont = true;
  
      for (unsigned fontIndex = 0; ; ++fontIndex) {
          const FontData* fontData = fontDataAt(fontDescription, fontIndex);
          if (!fontData) {
              // All fonts are custom fonts and are loading. Return the first FontData.
              fontData = fontDataAt(fontDescription, 0);
              if (fontData)
                  return fontData->fontDataForCharacter(space);
  
              SimpleFontData* lastResortFallback = FontCache::fontCache()->getLastResortFallbackFont(fontDescription).get();
              ASSERT(lastResortFallback);
              return lastResortFallback;
          }
  
          if (fontData->isSegmented() && !toSegmentedFontData(fontData)->containsCharacter(space))
              continue;
  
          const SimpleFontData* fontDataForSpace = fontData->fontDataForCharacter(space);
          ASSERT(fontDataForSpace);
  
          // When a custom font is loading, we should use the correct fallback font to layout the text.
          // Here skip the temporary font for the loading custom font which may not act as the correct fallback font.
          if (!fontDataForSpace->isLoadingFallback())
              return fontDataForSpace;
  
          if (fontData->isSegmented()) {
              const SegmentedFontData* segmented = toSegmentedFontData(fontData);
              for (unsigned i = 0; i < segmented->numRanges(); i++) {
                  const SimpleFontData* rangeFontData = segmented->rangeAt(i).fontData().get();
                  if (!rangeFontData->isLoadingFallback())
                      return rangeFontData;
              }
              if (fontData->isLoading())
                  shouldLoadCustomFont = false;
          }
  
          // Begin to load the first custom font if needed.
          if (shouldLoadCustomFont) {
              shouldLoadCustomFont = false;
              fontDataForSpace->customFontData()->beginLoadIfNeeded();
          }
      }
  }
  
  PassRefPtr<FontData> FontFallbackList::getFontData(const FontDescription& fontDescription, int& familyIndex) const
  {
      RefPtr<FontData> result;
  
      int startIndex = familyIndex;
      const FontFamily* startFamily = &fontDescription.family();
      for (int i = 0; startFamily && i < startIndex; i++)
          startFamily = startFamily->next();
      const FontFamily* currFamily = startFamily;
      while (currFamily && !result) {
          familyIndex++;
          if (currFamily->family().length()) {
              if (m_fontSelector)
                  result = m_fontSelector->getFontData(fontDescription, currFamily->family());
  
              if (!result)
                  result = FontCache::fontCache()->getFontData(fontDescription, currFamily->family());
          }
          currFamily = currFamily->next();
      }
  
      if (!currFamily)
          familyIndex = cAllFamiliesScanned;
  
      if (result || startIndex)
          return result.release();
  
      // If it's the primary font that we couldn't find, we try the following. In all other cases, we will
      // just use per-character system fallback.
  
      if (m_fontSelector) {
          // Try the user's preferred standard font.
          if (RefPtr<FontData> data = m_fontSelector->getFontData(fontDescription, FontFamilyNames::webkit_standard))
              return data.release();
      }
  
      // Still no result. Hand back our last resort fallback font.
      return FontCache::fontCache()->getLastResortFallbackFont(fontDescription);
  }
  
  
  const FontData* FontFallbackList::fontDataAt(const FontDescription& fontDescription, unsigned realizedFontIndex) const
  {
      if (realizedFontIndex < m_fontList.size())
          return m_fontList[realizedFontIndex].get(); // This fallback font is already in our list.
  
      // Make sure we're not passing in some crazy value here.
      ASSERT(realizedFontIndex == m_fontList.size());
  
      if (m_familyIndex == cAllFamiliesScanned)
          return 0;
  
      // Ask the font cache for the font data.
      // We are obtaining this font for the first time.  We keep track of the families we've looked at before
      // in |m_familyIndex|, so that we never scan the same spot in the list twice.  getFontData will adjust our
      // |m_familyIndex| as it scans for the right font to make.
      ASSERT(FontCache::fontCache()->generation() == m_generation);
      RefPtr<FontData> result = getFontData(fontDescription, m_familyIndex);
      if (result) {
          m_fontList.append(result);
          if (result->isLoadingFallback())
              m_hasLoadingFallback = true;
      }
      return result.get();
  }
  
  } // namespace blink
  